I recently updated the firmware on my router from 1.2.5 Build 20190411 rel.52981 to the latest version available on the site: ArcherC5400(EU)_V2_210308. This version is not found by the internal firmware check in the router.

Upgrading went fine, I saw no special issues. I did experience a better performance and full use of available bandwith, the reason for upgrading the firmware. See the issues on the forum about that.

But, after about 2 days, none of my devices could connect to the wifi. The network was still found, but none could connect. No authentication errors, just failing to connect. This goes for Linux laptops, Android phones, iPhone, iPad, MacBook, HP Printer. Every device. Pretty sure it's not the device that is having the issue. Switching off and on solves the issue. For 2 days that is, then the issue returns.

To make sure it's not a failed firmware update, I did a hard reset, did a new firmware upgrade and did not use a backup of my settings to configure the router again. Unfortunatelly, after about two days, no device can connect to the wifi.

Any suggestion on how to solve this is much appreciated. I just did a firmware downgrade on the device, but have no idea if this will help. Will know in about two days ;-)